JPH05332637A - Air conditioner - Google Patents

Abstract

(57) [Summary] [Objective] In an air conditioner capable of performing simultaneous cooling and heating operations in a plurality of indoor units, the object is to reduce the amount of refrigerant charge and reduce the cost of the device. [Structure] A control valve having a plurality of outdoor heat exchangers 3a, 3b having different heat exchange capacities (capacity), and always flowing refrigerant to the outdoor heat exchanger 3a having a small heat exchange capacity during simultaneous heating / cooling operation (outdoor electric Type expansion valves) 14a, 14b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner composed of an outdoor unit and a plurality of indoor units, one indoor unit being capable of cooling operation and the other indoor unit being capable of heating operation at the same time. ..

[0002]

2. Description of the Related Art Among a plurality of indoor units, the applicant has proposed JP-A-3-55474 as an air conditioner in which one indoor unit can perform a cooling operation and the other outdoor unit can simultaneously perform a heating operation. ing.

The air conditioner disclosed in this publication is provided with a plurality of outdoor heat exchangers having different heat exchange capacities (hereinafter referred to as "heat exchange capacity"), and for example, a plurality of outdoor heat exchanges can be performed during simultaneous cooling and heating operations. When the reactor acts as a condenser, the condensing capacity is adjusted by selectively flowing the refrigerant to the outdoor heat exchanger having the heat exchanging capacity according to the magnitude of the load (condensing capacity).

[0004]

In such an air conditioner, even if the refrigerant is selectively flown to the outdoor heat exchanger having the heat exchange capacity according to the load (condensation capacity), the outside air temperature If the value is low (about 20 ° C.), the performance more than necessary may be exhibited. In this way, when the capacity exceeding the necessary level is exhibited, the liquid refrigerant is stored in this heat exchanger to reduce the effective heat transfer area in the heat exchanger and bring the capacity of the heat exchanger to a predetermined value. I try to keep it down.

As described above, in order to store the liquid refrigerant in the heat exchanger, it is necessary to charge the air conditioner with a refrigerant having a refrigerating capacity or more, which inevitably results in an increase in cost.

Further, in order to finely control the condensing capacity of the outdoor heat exchanger, a large number (for example, 3 or more) of outdoor heat exchangers having different heat exchange capacities may be provided. However, the cost increase was inevitable.

An object of the present invention is to reduce the amount of refrigerant charge and reduce the cost in an air conditioner capable of performing simultaneous cooling and heating operations in a plurality of indoor units.

[0008]

In order to achieve this object, the present invention provides a plurality of outdoor heat exchangers having different heat exchange capacities as condensers while performing simultaneous cooling / heating operation in a plurality of indoor units. A control valve is provided which always causes the high temperature refrigerant to flow to the outdoor heat exchanger having a small heat exchange capacity.

[0009]

Function When a plurality of outdoor units having different heat exchange capacities are used as condensers for simultaneous cooling and heating operation in a plurality of indoor units, the refrigerant is always flowed to the outdoor heat exchanger having a small heat exchange capacity, Refrigerant is not stored in the outdoor heat exchanger having a capacity higher than the required capacity.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 denotes an outdoor heat exchanger 3a having different heat exchange capacities (capacities) from a variable capacity compressor 2a and a constant capacity compressor 2b (for example, 3.5 horsepower and 5.0 horsepower). , 3
b, an outdoor unit having a gas-liquid separator 4 and 5a, 5b
Is an indoor unit having indoor heat exchangers 6a and 6b, which branches the refrigerant discharge pipe 7 and the refrigerant suction pipe 8 of the compressors 2a and 2b and connects the branched pipes to one end of each of the outdoor heat exchangers 3a and 3b. While being connected via the outdoor switching valves 9a, 9b, 10a, 10b, the outdoor unit 1 and the indoor units 5a, 5
An inter-unit pipe (refrigerant pipe) 11 that connects b with a high-pressure gas pipe 12 that is branched and connected to a refrigerant discharge pipe 7, a low-pressure gas pipe 13 that is branched and connected to a refrigerant suction pipe 8, and an outdoor heat exchanger 3
The other ends of a and 3b and the outdoor electric expansion valve (control valve) 14
and a liquid pipe 16 connected via a and 14b,
One end of each indoor heat exchanger 6a, 6b is connected to a high pressure gas pipe 12 and a low pressure gas pipe 13, respectively, and indoor side switching valves 17a, 17b, 1 are provided.
The liquid pipe 16 is branched and connected via 8a and 18b, and is connected to the liquid pipe 16 through indoor electric expansion valves 19a and 19b.

Reference numeral 20 denotes a controller, which is a valve for each of the outdoor electric expansion valves 14a, 14b based on the values detected by the sensors 21a, 21b built in the indoor unit and the sensor 21c built in the outdoor unit 1. The opening is controlled, and the control content is shown in FIG.

Although not shown, the above-mentioned indoor unit 5
The number of a and 5b is not limited to two and is three or more. For example, the three indoor units 5a and 5b can perform the cooling operation and the heating operation at the same time. Also two indoor units 5a
When one indoor unit 5b simultaneously performs the heating operation, the main operation is the cooling operation, and the outdoor heat exchangers 3a and 3b act as condensers at this time. While 2
When one indoor unit 5a and the like perform a heating operation and one indoor unit 5b simultaneously performs a cooling operation, the heating-based operation is performed, and at this time, the outdoor heat exchangers 3a and 3b act as evaporators.

FIG. 2 is a cross-sectional view of the outdoor unit 1, in which the outdoor heat exchanger 3b having a large capacity (5 horsepower) is placed at the bottom and the small capacity (3.5 horsepower).
The outdoor heat exchangers 3a of horsepower are stacked so that they are on top. An outdoor fan 22 is arranged above the inside of the outdoor unit, that is, at a position close to the small-capacity outdoor heat exchanger 3a. Then, by the rotation of the outdoor fan 22, the outside air is sucked from the suction ports 23 on both side surfaces of the outdoor unit 1 and discharged from the air outlet 24 on the upper surface.

Next, the driving operation will be described. When both the indoor units 5a and 5b are to be cooled, the one outdoor switching valve 9a and 9b is opened and the other outdoor switching valve 1 is opened.
0a, 10b are closed, and one indoor side switching valve 17a,
17b is closed and the other indoor side switching valves 18a, 18
By opening b, the refrigerant discharged from the compressors 2a, 2b flows in parallel from the discharge pipe 7 with the switching valves 9a, 9b and the outdoor heat exchangers 3a, 3b, where they are condensed and liquefied, and then the chamber in the fully opened state. It is distributed via the outer electric expansion valves 14a and 14b and the liquid pipe 16 to the electric expansion valves 19a and 19b on the indoor side, where the pressure is reduced. After that, after evaporating and vaporizing in the indoor heat exchangers 6a and 6b, the indoor side switching valves 18a and 18b, the low pressure gas pipe 13, the suction pipe 8 and the gas-liquid separator 4 are sequentially passed to the compressors 2a and 2b. Inhaled. In this way, all the rooms are simultaneously cooled by the indoor heat exchangers 6a and 6b acting as evaporators.

On the contrary, when both the indoor units 2a and 2b are to be heated, the outdoor switching valves 9a and 9b are closed and the outdoor switching valves 10a and 10b are opened.
And by opening one indoor side switching valve 17a, 17b and closing the other indoor side switching valve 18a, 18b,
The refrigerant discharged from the compressors 2a and 2b is sequentially distributed through the discharge pipe 7 and the high-pressure gas pipe 12 to the switching valves 17a and 17b and the indoor heat exchangers 6a and 6b, where they are condensed and liquefied, respectively, and then fully opened. After passing through the indoor electric expansion valves 19a and 19b, they are joined by the liquid pipe 16, and after that, the pressure is reduced by the outdoor electric expansion valves 14a and 14b and the outdoor heat exchangers 3a and 3b.
After being evaporated and vaporized by, the switching valves 10a, 10b, the suction pipe 8,
It is sucked into the compressors 2a and 2b through the gas-liquid separator 4 in order. Each indoor heat exchanger 6 thus acting as a condenser
All rooms are heated simultaneously by a and 6b.

Next, while operating the outdoor heat exchangers 3a and 3b as condensers, at the same time, one indoor unit 5a and a third indoor unit (not shown) are cooled and the other indoor unit 5b is heated. The case (cooling main operation) will be described. In this case, the indoor sensors 21a and 21b detect the cooling load and the heating load in each room, and the outdoor sensor 21c detects the outside air temperature. These detected values are input to the controller 20, and in this controller 20, the difference between the cooling load and the heating load (condensing capacity in the outdoor heat exchanger).
Is larger or smaller than a predetermined value and the opening degree of each of the outdoor electric expansion valves 14a, 14b is controlled as follows according to the outside air temperature. First, when the difference between the cooling load and the heating load is smaller than a predetermined value and the outside air temperature is low, the condensing capacity of the outdoor heat exchangers 3a and 3b is small, and therefore the outdoor heat exchanger with the smaller heat exchange capacity is sufficient. 3a of one outdoor side switching valve 9a is opened, and the other outdoor side switching valve 10a and the switching valve 9 of both the outdoor heat exchanger 3b having the larger heat exchange capacity.
b, 10b are closed, and one indoor side switching valve 17a of the indoor unit 5a for cooling is closed, the other indoor side switching valve 18a is opened, and one indoor side switching valve 17b of the indoor unit 5b for heating is opened. When the other indoor-side switching valve 18b is closed together, a part of the refrigerant discharged from the compressors 2a and 2b flows to only one outdoor heat exchanger 3a via the discharge pipe 7 and the switching valve 9a, and the remaining refrigerant. Flows to the one indoor side switching valve 17b of the indoor unit 5b for heating via the high pressure gas pipe 12 and the indoor heat exchanger 6b, and is condensed and liquefied by the indoor heat exchanger 6b and the outdoor heat exchanger 3a.
The refrigerant condensed and liquefied in the heat exchangers 6b and 3a is in the fully opened state, the electric expansion valves 14a and 19b, and the liquid pipe 16
After being decompressed by the electric expansion valve 19a of the indoor unit 5a, it is evaporated and vaporized by the indoor heat exchanger 6a, and then joined by the low pressure gas pipe 13 through the indoor side switching valve 18a, and the suction pipe 8, It is sucked into the compressors 2a and 2b through the gas-liquid separator 4 in order. In this way, the indoor unit 5b that operates as a condenser performs the heating operation of the indoor unit 5b, and the other indoor heat exchanger 6a that functions as an evaporator performs the cooling operation of the indoor unit 5a (see the solid line arrow). At this time, the switching valve 9b,
By closing 10b and opening the outdoor electric expansion valve 14b, the outdoor heat exchanger 3b having a large heat exchange capacity (capacity).
The refrigerant stored in the liquid pipe 1 passes through the expansion valve 14b.
6 (see dashed arrow).

Thus, when the difference between the cooling load and the heating load (condensation capacity in the outdoor heat exchanger) is smaller than the predetermined value and the outside air temperature is low in the cooling-main operation, the heat of the larger heat exchange capacity is used. Refrigerant in the exchanger 3b is collected as indicated by a broken line arrow, and the indoor heat exchangers 6a, 6 of the both indoor units 5a, 5b are collected.
b and the outdoor heat exchanger 3a having a small heat exchange capacity.

As the difference between the cooling load and the heating load (condensing capacity in the outdoor heat exchanger) increases and / or the outside air temperature rises, the opening degree of the outdoor electric expansion valve 14a is increased, The amount of refrigerant flowing out of the outdoor heat exchanger 3a is increased.

Here, the heat exchange capacity of the outdoor heat exchanger 3a greatly varies depending on the outside air temperature, and according to the experimental results, this heat exchange capacity of about 3.5 horsepower at an outside air temperature of 35 ° C. is obtained. As shown in FIG. 3, the exchanger 3a has an outside air temperature of 20
It was confirmed that when the temperature was lowered to ℃, the heat exchange capacity increased to about 8 to 9 horsepower. And during the above-mentioned cooling-main operation, the outside temperature is 20 ° C as in April-May and September-October.
Since it is often done in the middle period, it is mentioned in 3. above.
Even in the case of the outdoor heat exchanger 3a having a small heat exchange capacity of about 5 horsepower under the conditions in the region (a) of FIG. 3, the outdoor electric expansion valve 1
By controlling the opening degree of 4a, the outdoor heat exchanger 3a of about 3.5 horsepower can be used as an outdoor heat exchanger of about 8 to 9 horsepower. Moreover, since this outdoor heat exchanger 3a is located in the vicinity of the outdoor fan 22 as shown in FIG. 2, the ventilation amount can be secured more than that of the outdoor heat exchanger 3b, and the heat exchange efficiency can be improved. It is better.

As described above, in the simultaneous cooling / heating simultaneous operation mainly in the cooling operation, there are many cases in the region of A in FIG. In this way, by controlling the opening degree of the outdoor electric expansion valve 14a, the amount of the refrigerant flowing into (flowing out from) the outdoor heat exchanger 3a, which is as small as possible, is controlled to adjust the condensation capacity in the outdoor heat exchanger 3a. Therefore, it is possible to reduce the refrigerant charge amount in the air conditioner, as compared with the conventional case in which the outdoor heat exchanger stores the refrigerant to adjust the heat capacity of the outdoor heat exchanger. it can.

In the area B of FIG. 3, that is, when the difference between the cooling load and the heating load and / or the outside air temperature exceeds a predetermined value, the outdoor electric expansion valve 14a is half-opened (about half the full open). And the opening degree of the outdoor electric expansion valve 14b is controlled according to the above-mentioned difference. As a result, in the outdoor unit 1, the refrigerant flows in parallel to the two outdoor heat exchangers 3a and 3b, and a sufficient condensing capacity can be secured. Fig. 4 shows 2 when the outside air temperature is 35 ° C.
The opening degrees of the two outdoor electric expansion valves 14a and 14b are shown. When the condensation load is small (3.5 horsepower or less), the opening control of only one outdoor electric expansion valve 14a is performed.
When the condensation load is large (3.5 or more), both expansion valves 14
Open a and b.

Regarding the control during the operation mainly for cooling, the flow chart as shown in FIG. 5 is shown if the expansion valves 14a and 14b are mainly shown. When the operation mainly for cooling is started, in step 50, the indoor sensors 21a and 21b and the outdoor sensor 21 are
The condensing load and the outside air temperature are detected at c. Next, step 5
In step 1, it is determined whether the value detected in step 50 is in the area of FIG. If it is in the region B, the process proceeds to step 52, and the opening degree of only the outdoor electric expansion valve 14a is controlled. That is, the expansion valve 14a is set so that the refrigerant flows only in one outdoor heat exchanger 3a, and the step 53 is performed.
The compressors 2a and 2b are operated according to the air conditioning load.

On the other hand, if the value detected in step 50 is the area B in FIG. 3, the process proceeds to step 54 through step 51, and one of the outdoor electric expansion valves 14a is in a half-opened state, and the other outdoor The opening degree of the electric expansion valve 14b is controlled according to the condensation load. That is, the two outdoor heat exchangers 3
Both expansion valves are set so that the refrigerant flows in parallel to a and 3b, and in step 53, the compressors 2a and 2b are operated according to the air conditioning load.

[0024]

As described above, according to the present invention, while operating a plurality of outdoor heat exchangers having different heat exchange capacities as a condenser, the refrigerant always has a heat exchange capacity when performing the simultaneous cooling / heating operation in a plurality of indoor units. The outdoor heat exchanger, which has a small heat exchange capacity, is used effectively during simultaneous cooling and heating operations, so the amount of refrigerant charge in the air conditioner can be kept low and the cost of this device can be reduced. Can be down.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram of an air conditioner of the present invention.

FIG. 2 is an explanatory diagram showing an internal structure of an outdoor unit of the air conditioner shown in FIG.

FIG. 3 is a characteristic diagram showing a change in capacity according to the outside air temperature in the outdoor heat exchanger having a small heat exchange capacity of the outdoor unit shown in FIG.

FIG. 4 is an illustration showing the opening degrees of the two outdoor electric expansion valves shown in FIG.

5 is a flowchart showing a control operation of the controller shown in FIG.

[Explanation of symbols]

 1 Outdoor unit 2a, 2b Compressor 3a, 3b Outdoor heat exchanger 5a, 5b Indoor unit 11 Inter-unit piping (refrigerant pipe) 14a, 14b Outdoor-side electric expansion valve (control valve)

Claims (1)

[Claims] 1. An indoor unit comprising an outdoor unit in which a compressor and a plurality of outdoor heat exchangers having different heat exchange capacities are housed, and a plurality of indoor units, and the indoor unit and the outdoor unit are connected by a refrigerant pipe to provide one indoor unit. In an air conditioner in which the other indoor unit performs a heating operation at the same time,
When operating the plurality of outdoor heat exchangers as a condenser during the cooling / heating simultaneous operation, a control valve is provided which causes the refrigerant to always flow to a heat exchanger having a small heat exchange capacity among these outdoor heat exchangers. Air conditioner.